The present invention relates to an encoscope in which a direct-vision attachment and a side-vision attachment can be exchangeably attached as the attachment on the examining or distal end of the endoscope.
An endoscope in which a direct-vision attachment and a side-vision attachment is exchangeably attached to an object lens on the distal end of the endoscope so that one endoscope can be used as both of direct-vision and side-vision endoscopes has been known. An endoscope of this type is disclosed for example, in Japanese Laid-Open Utility Model Publication No. 62-184515.
In this conventional technique, the attachment is attached and fixed to the distal end portion of the endoscope by means of a pin inserted in the distal end portion or a thread is formed on the distal end portion.
However, the conventional attachment means is insufficient in that the attachment means is loosened by vibration or heat in an object to be examined, in which the endoscope is inserted, and there is a risk of falling of the object lens.
For example, in the case where the interior of a jet engine is inspected by the endoscope, falling of the attachment in the engine results in occurrence of a grave accident. Similarly, there is a risk of falling of the attachment when the body cavity is examined by the endoscope.
It is a primary object of the present invention to provide a direct vision/side vision exchangeable endoscope in which the attachment is kept attached even if the anchoring ring comes off, and falling of the attachment is prevented.
Another object of the present invention is to provide a direct vision/side vision exchangeable endoscope in which the effect of preventing falling of the attachment is similarly attained, even if the anchoring ring is freely set on the distal end portion.
Still another object of the present invention is to provide a direct vision/side vision exchangeable endoscope in which an operator can be informed of the loosing of the anchoring ring and occurrence of an accident can be prevented, in case of the side-vision attachment.
Still a further object of the present invention is to provide a direct vision/side vision exchangeable endoscope in which the anchoring ring and the attachment are presented from simultaneously coming off under the same conditions, even if there are motions in one direction of the endoscope, and an assured securement can be expected.